Local Division Dusseldorf on admissibility of new lines of attack

Local Division Dusseldorf on admissibility of new lines of attack based on timely introduced prior art in revocation counterclaim proceedings

Case Overview

The Local Division in Dusseldorf recently addressed the admissibility of new prior art introduced in a reply to a revocation counterclaim. The decision, issued on 8 May 2025, clarified the procedural framework under R. 263 RoP for introducing additional prior art, or merely new lines of attack base on already introduced prior art, in ongoing revocation proceedings.

The Court's Order

The Court emphasized that introducing new prior art to challenge novelty or inventive step in a reply to a revocation counterclaim constitutes an extension of the counterclaim within the meaning of R. 263 RoP. This is only permissible if the defendant demonstrates that the cited prior art could not have been presented earlier with the original counterclaim despite the exercise of due care and that admitting this new prior art does not unduly impair the claimant's ability to conduct the proceedings effectively.

The Court specifically noted that:

• The inclusion of new prior art in a reply is considered an amendment of the case and must be justified by showing that it could not have been included earlier.
• The introduction of a new line of attack based on already submitted prior art, if first raised in the reply, also requires a similar justification. This includes demonstrating that the new argument could not have been presented with the original counterclaim, even with due diligence.
• The burden is on the defendant to substantiate why the newly introduced documents or lines of attacks, respectively, were not included in the original counterclaim and to show that the claimant's procedural position is not unfairly affected by the late introduction.

Our key takeaway

A revocation (counter) claimant seeking to introduce a new prior art after the first submission, e.g. at the reply stage, must meet a high burden, including demonstrating due diligence and the absence of procedural prejudice to the opposing party.

The same applies to a new line of attack based on timely submitted prior art.

To the decision To the Blog Overview